title: Rare earth-cobalt hard magnetic nanoparticles and nanoflakes by high-energy milling.
abstract: High-energy ball milling has been shown to be a promising method for large-scale fabrication of rare earth-transition metal nanoparticles. In this work, we report crystallographically anisotropic SmCo(5), PrCo(5) and Sm(2)(Co, Fe)(17) nanoparticles (particle size smaller than 10 nm) obtained by surfactant-assisted ball milling and study their size and properties as a function of the milling conditions. By milling nanocrystalline precursor alloys, we obtained SmCo(5) platelets (flakes) approximately 100 nm thick with an aspect ratio as high as 10(2)-10(3). The unusual shape evolution of this brittle material is attributed to its increased plasticity in the nanocrystalline state. The nanoflakes are susceptible to re-crystallization annealing and exhibit a room-temperature coercivity of up to 19 kOe. The successful fabrication of rare earth-cobalt nanoparticles and ultra-thin flakes provides hope for the development of nanocomposite permanent magnets with an enhanced energy product.
authors.affiliation: Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA. gabay@physics.udel.edu
authors.forename: A M
authors.initials: AM
authors.lastname: Gabay
authors.forename: N G
authors.initials: NG
authors.lastname: Akdogan
authors.forename: M
authors.initials: M
authors.lastname: Marinescu
authors.forename: J F
authors.initials: JF
authors.lastname: Liu
authors.forename: G C
authors.initials: GC
authors.lastname: Hadjipanayis